In crucible furnaces in which one electrode is a sacrificial metal electrode, a graphite electrode is usually connected as the cathode, while the sacrificial metal electrode operates as an anode.
A crucible furnace employing direct current which has an arc electrode operating as a cathode is known from German published patent Document DE-OS 31 07 454. Contact blocks of a metal are provided close to the bottom area of the furnace vessel. The contact blocks are on the side turned toward the center of the furnace vessel, which is provided with refractory brick with conductive inserts. Since this device has laterally connected contact electrodes, it is supposed to achieve the advantage that the bottom remains free for bottom tap holes. However, this device has the disadvantage that, when the contact blocks are consummed or damaged, replacement work is difficult and costly, since the contact blocks are solidly connected to the vessel.